quadro is a workstation class card.
not used for gaming, they have special optimizations in drivers and possibly hardware so they get much much better performances in CAD apps. the quadro cards however have their gaming counterparts the Geforces and usually they utilize the exact same GPU's.
in short
quadro sux for games, geforce is good for games
quadro is good for CAD and the like, Geforce sux for CAD
though each can still do each others job, just not as well